It was the winter 1998 when the Colts began an intricate and detailed evaluation of top college quarterbacks Ryan Leaf and Peyton Manning.

Owning the first pick in the upcoming NFL Draft, they broke down every possible component of the two potential top choices.

There were reports several general managers were in favor of Leaf, the Washington State gunslinger, over Tennessee’s Manning. The consensus, then Colts general manager Bill Polian recalled, was Leaf had the higher physical upside.

“There was a lot of noise out there — where it got started to this day, I don’t know; they were wives’ tales — [Manning] had a weak arm, he was a poor athlete, he was a product of the system, whatever that meant,” Polian, an analyst with ESPN and SiriusXM, told The Post on Radio Row Thursday night in Midtown. “And Leaf was just the opposite. Leaf was a great competitor. Leaf had a much stronger arm, he was much more athletic.”

The Colts, their analysis already pointing heavily in Manning’s favor, worked out each player individually. And all the talk merely was hot air.

“When you went to the workouts, just the opposite was true,” Polian recalled with a smile. “It was surprising in the sense you had heard so much the opposite.”

Debate over.

Manning would go on to produce a certain Hall of Fame career, reaching three Super Bowls with two different franchises, owning a number of NFL records and winning four MVPs, while Leaf was a complete bust, throwing 36 interceptions in three underwhelming seasons.

Polian said the Colts saw a stark difference between the two, not just in the quarterbacks’ physical tools, but in Manning’s smarts, poise under pressure and vastly superior work ethic.”

“For us, internally, once we did all of our due diligence, there was no choice,” Polian said. “It was Peyton, clearly.”

Polian said if any other player would have rebounded from four neck surgeries the way Manning has, setting the NFL record for most touchdown passes this year at the age of 37, he would have called it astounding. But not for Manning.

“In Peyton Manning’s case, nothing surprises me,” Polian said. “He’s a once-in-a-lifetime player, you’re not going to see his like again. It will be another generation before anybody even approaches that.”

The former GM said he believes Manning will pick apart the Seahawks’ vaunted secondary on Sunday, given time to throw. That’s not a knock on the Legion of Doom, he said, just a credit to the kind of marksmen Manning is when given time.

“The key is does Denver’s offensive line have the capability to keep him clean and let him do his thing,” Polian said. “I think [Seattle will] be able to cover, but he gets the ball into windows that are the tightest windows in football, and he knows where the matchups are. … If he has time to do all that, I believe he’ll do fine.”